Patients with the diffuse forms of systemic lupus erythematosus nephritis previously entered into therapeutic trials continue to be evaluated. Long-term studies suggest that the degree of scarring on the renal biopsy may provide important prognostic information. The subset of patients with a mild degree of scarring responds to oral azathioprine or oral cyclophosphamide when added to low doses of corticosteroids. Patients with a greater degree of scarring are not effectively treated with those drug programs, but may respond to intravenous boluses of cyclophosphamide. The relative effectiveness and toxicity of various drug programs continues to be systematically evaluated. Long-term follow-up of patients with lupus nephritis demonstrate clear-out benefit of immunosuppressive-cytotoxic drugs over conventional corticosteroid therapy. The benefit was greatest with cyclophosphamide. The differences are highly significant, but only are apparent when follow-up is substantially beyond the 5 year point. Intermittent boluses of cyclophosphamide are at least as effective as oral cyclophosphamide and are much less toxic.